The first surfboards were simple, substantially flat boards used for riding waves. Modern surfboards typically include one or more fins attached to the underside of the board which allow the surfer greater control over speed and trajectory. The size, shape, and angle of the fin or fins are significant factors in how the surfboard handles under various conditions. It is common for surfboards to be constructed with a standard finbox that allows the attachment and removal of fins having corresponding standard connectors. This allows the surfer to switch between fins having various properties depending on the conditions and the surfer's preferences. Among the properties that can be varied by fin selection is attack angle, which is the angle of the fin relative to the longitudinal axis of the surfboard. In some situations, performance could be improved by a fin capable of swinging through a range of attack angles during the course of a single ride. A fin that swings freely through all possible attack angles, however, would make the surfboard difficult to control and could be dangerous to the surfer. A surfboard fin capable of swinging through a variety of attack angles and yet having the attack angle sufficiently constricted to be useful does not appear to be provided by the prior art.